一种基于2.4GHz频段的宽带射频发射机的研制

在现代无线通信系统中,研制宽带无线发射机成为射频无线电的发展趋势。以采用ADI公司的ADF4115和MAXIM公司的MAX2750构成的锁相环路提供2880MHz的射频信号源,以ADI公司的AD9857将基带信号调制为70MHz的QPSK信号,再以MAXIM公司的MAX2671作为直接上变频器,从而可以设计出一款工作在2．4GHz频段的宽带射频发射机,从而满足红外图像信号等大信息量数据的无线传输。     

ADI发布支持多种无线标准的正交调制器

ADI公司5月8日发布了五款能覆盖250MHz～4 GHz频率范围的引脚兼容正交调制器系列产品以扩展其射频(RF)集成电路(IC)产品,从而允许无线系统设计工程师按照多种工作频段和蜂窝手机标准实现标准化印制电路板(PCB)设计.这些调制器是用来将复数调制信号例如语音、数据或模拟视频信号从基带信号直接上变频到RF频率.ADI公司新的正交调制器可以在输出更高功率的同时提供具有更好线性度的调制信号,从而无需在发射信号链中使用中频电路级即可提高传输质量并且降低系统成本.     

一种应用于无线通信领域的新型发射机的研制

本文设计的这款新型发射机，可应用于2G／3G移动通信系统，固定宽带接入系统和无线局域网等众多的无线通信领域。该设计采用的是直接射频技术，应用CPLD产生基带所需的数据，锁相环设计产生900MHz的载频信号，并利用ADI公司的AD8345完成正交射频调制。并给出了相应的软件仿真结果和发射机硬件实验模型的测试结果。     

400MHz PSK卫星通信调制器的设计

卫星数据通信往往采用PSK调制方式传输数据信号,本文介绍采用DDS芯片AD7008组成的400MHz卫星通信PSK调制器的电路设计方法,利用集成DDS调制芯片AD7008方便地实现PSK调制,再采用锁相环路把调制信号搬到400MHz载频上,最后给出了该PSK调制器的性能指标。     

新品发布

集成电路Integrated Circuits高线性度620～1100MHz正交调制器LT5571为850～965MHz GSM、CDMA2000、ISM和RFID调制器应用进行了优化。该器件接受I(同相)和Q(正交相位)基带信号并将其直接调制至射频信号。其在900MHz时,OIP3(输出3阶截取点)为21.7dBm,OIP2(输出2阶截取点)为63.8dBm,同时在采用5V电源时仅消耗97mA静态电流。     

AD8345正交调制器及其应用

AD8345是ANALOG DEVICES公司推出的一种正交调制器，其工作频率为250MHz～1000MHz，在数字通信系统中可用作中频调制器或直接上变频器，该产品具有输出信号频带宽、本振信号泄漏低、边带抑制作用强等特点，本文介绍了AD8345的性能特点、内部结构、引脚定义以及具体应用设计，并给出了典型应用电路。     

可编程器件

高线性度直接转换正交调制器凌特公司(Linear Technology Corporation)新推出的高性能正交调制器,为850MHz～965MHz GSM、CDMA2000、ISM和RFID调制器应用而优化。LT5568接受I(输入相位)和Q(正交相位)基带信号并直接调制到射频传输频率上。其零中频(Zero-IF)发送器架构使基站设计师能够获得高性     

一种PSK卫星通信调制器的设计

卫星数据通信PSK信号的调制有多种方法,本文介绍采用专用的DDS调制芯片AD7008完成在2.1～2.3MHz载频上PSK调制,再将2.1～2.3MHz的PSK调制信号用PLL环路把它搬到400MHz载频上,从而实现400MHz PSK调制方法。文中给出了调制器的电路设计方法和性能指标。     

基于AD9957的双通道高速数字调制信号源设计

介绍了ADI公司具有内部调制功能的高速DDS器件AD9957的特点与应用,并提出了一种全新的高速调制信号源设计方案,给出了硬件结构框图和软件流程,详细介绍了系统工作原理.实践证明,输出正弦波最高频率达400 MHz,调制波调制速度可达1 MHz.     

Design of High Frequency and Multi-mode Signal Generator Based on AD9910

以ADI公司的高性能DDS芯片AD9910为核心,以TI公司的低功耗单片机MSP430为控制器,设计了一种信号发生器.目前的信号发生器产生信号单一,频率较低,不能满足某些需要多模式高频信号场合的要求,为了解决这个问题,采用单片机直接控制DDS芯片的方法,设计了一种能产生高频多模式信号的信号发生器,能够输出高达400 MHz的信号,频率分辨力可达0.23 Hz,还能够进行多级的相移键控和频移键控调制.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.